A noise indication system, “SoundEar®”, is known that may be set up with multiple microphone units distributed in a room or a suite of rooms, such as e.g. an open office or a workshop, and one or more display units located in the same room or suite of rooms. Each microphone unit measures acoustic noise levels at its location and transmits the measured acoustic noise levels to one or more of the display units, which display the current noise level in a symbolic fashion. The noise indication system gives visual feedback about the noise levels, thereby making office and workshop workers aware of their own noise contribution, which may generally aid in lowering the overall noise level. Ideally, each office desk or work location should be equipped with a microphone unit. In larger rooms with many workers, the microphone units may thus make the noise indication system rather expensive, and they may further contribute to cluttering of desktops and workbenches.
Headsets for use with telephone networks and other audio communication networks have been known for many years, and they typically comprise a microphone for picking up the wearer's voice as well as one or two earphones for providing acoustic output signals to one or both of the wearer's ears. Audio signals output by the microphone are typically amplified in a switch board or a base station connected between the headset and the telephone system and the amplified signals are provided to a telephone line of the telephone system. The switch board or base station may also amplify audio signals received from the telephone line before providing them to the headset earphone or earphones. Some known telephone systems allow interconnecting more than two parties in a so-called conference call so that one or more of the parties can receive audio signals from multiple other parties.